Set zero spaces after fn keyword to follow PER-CS2.0

https://github.com/php-fig/per-coding-style/blob/2.0.0/spec.md#71-short-closures

Author: alies-dev

IxDFCodingStandard/ruleset.xml

@@ -291,7 +291,11 @@
     <rule ref="SlevomatCodingStandard.Exceptions.ReferenceThrowableOnly"/>
     <rule ref="SlevomatCodingStandard.Exceptions.RequireNonCapturingCatch"/>
     <rule ref="SlevomatCodingStandard.Files.FileLength"/>
-    <rule ref="SlevomatCodingStandard.Functions.ArrowFunctionDeclaration"/>
+    <rule ref="SlevomatCodingStandard.Functions.ArrowFunctionDeclaration">
+        <properties>
+            <property name="spacesCountAfterKeyword" value="0"/>
+        </properties>
+    </rule>
     <rule ref="SlevomatCodingStandard.Functions.DisallowEmptyFunction"/>
     <rule ref="SlevomatCodingStandard.Functions.DisallowNamedArguments">
         <exclude-pattern>tests/*\.php</exclude-pattern>

composer.json

@@ -31,6 +31,7 @@
         }
     },
     "scripts": {
+        "cs": "@cs:fix",
         "cs:check": "phpcs -p -s --colors --report-full --report-summary --cache=.cache/phpcs",
         "cs:fix": "phpcbf -p --colors --cache=.cache/phpcs",
         "test": "phpunit",